package main

func addTwpNumbers(l1,l2 *ListNode)(head *ListNode){
	var tail *ListNode
	carry :=0
	for l1 !=nil || l2 !=nil{
		n1,n2:=0,0
		if l1 !=nil{
			n1 =l1.Val
			l1 =l1.Next
		}
		if l2 !=nil{
			n2 =l2.Val
			l2 =l2.Next
		}
		sum :=n1+n2+carry
		sum,carry =sum%10,sum/10
		if head == nil {
			head = &ListNode{Val:sum}
			tail =head
		}else{
			tail.Next = &ListNode{Val :sum}
			tail =tail.Next
		}
	}
	if carry >0{
		tail.Next =&ListNode{Val: carry}
	}
	return
}